The FiveThirtyEight Team Goes To Iowa

DES MOINES — The Iowa caucuses seem so close that I can almost taste them. Yet our FiveThirtyEight Iowa forecasts suggest that a lot of movement can happen between the polls taken now (19 days out) and the results on caucus night. We don’t need to look far back to see how much the numbers can move. The 2012 Republican race changed tremendously in the final 30 days of the Iowa campaign. In an average of polls completed 22 to 31 days before the caucuses (equivalent to surveys taken from Jan. 1 to Jan. 10 of 2016), the average candidate saw his or her support change by 6 percentage points. Much of that had to do with religious conservatives getting behind Rick Santorum, who climbed to 24.5 percent from 5.3 percent in that final month — in part because he gained a pivotal endorsement from social conservative leader Bob Vander Plaats. Many of those Santorum voters left Newt Gingrich, who fell to 13.3 percent from 28.9 percent over that period. It wasn’t just the socially conservative Iowa voters who were changing their tune in 2012. Mitt Romney went to 24.5 percent from 17.2 percent in the final month and ended up basically tied with Santorum for victory in the caucuses. Ron Paul came in a fairly close third place after rising to 21.4 percent from 15.8 percent. The point is that we still have time for a major shift in the campaign. The Des Moines Register poll conducted by Ann Selzer that came out today was completed 22 days before the vote, and it will not be the final word.